Field of the Invention
The present invention relates to a drug solution injection device for use in administrating a drug solution by using a microneedle.
Discussion of the Background
Methods of administering a drug, such as a vaccine, into the body include a well-known method making use of a microneedle (e.g., refer to PTL 1). Such a microneedle has a plurality of protrusions, each having a needle-shape, on a surface of a substrate. In the administration method using a microneedle, protrusions pierce the skin by the substrate being pressed against the skin, and the drug is fed into the skin from holes formed by the protrusions. The length of the protrusions is restricted to a length which does not reach the nerve cells of the dermal layer in the skin. Thus, in the administration method using a microneedle, pain is alleviated when the skin is pierced, compared to the administration method using an injection needle. Further, the administration method using a microneedle administers a drug into an intradermal area where antigen-presenting cells are abundantly present. Therefore, dosage of the drug can be reduced compared to a subcutaneous injection.
A drug administration method using a microneedle uses a microneedle in which a through hole is formed penetrating a substrate and a protrusion in a direction in which the protrusion extends, and a drug solution, which is a liquid drug, is intradermally administered through the through hole. Normally, when administering a drug solution by such a method, a device such as an applicator is used to assist the protrusion piercing the skin and the drug solution being fed into the through hole.
For example, there is a proposed device which is provided with a limiter for controlling the insertion depth of the protrusion into the skin, and a stabilizer for restraining the distortion of the skin around the protrusion, for the purpose of preventing a part of a drug solution from leaking to the skin surface or leaking subcutaneously during administration of the drug solution (refer to PTL 2). For example, there is another proposed device in which a spring is assembled around the microneedle to urge the protrusion to puncture the skin, and prevent the protrusion from being detached from the skin during administration of a drug solution (refer to PTL 3).
PTL 1: JP-A 2005-21677
PTL 2: JP-A 2009-516572
PTL 3: JP-A 2013-500773